Tablet dissolution testing is a very tedious job, and one of the more tedious aspects is the thorough washing of the dissolution vessels required after each test. To wash the dissolution vessels after each test, a user often must remove the dissolution vessels from the dissolution tester one by one, walk to a sink or other washing area to manually wash it and then walk back to the dissolution tester in order to put the cleaned dissolution vessel back into the dissolution tester in preparation for the next test.
One potentially dangerous situation which arises when washing the dissolution vessels is that upon removal from the dissolution tester, each dissolution vessel is usually full of dissolution media, and may contain acid or perhaps dangerous active ingredients from the tested tablet or other drug form. As such, it is very dangerous for the user to hold the dissolution vessel and walk around the testing facility, e.g., to the sink to manually wash it.
Another concern which arises during washing of dissolution vessels relates to the sufficiency of the washing process since there is no widely accepted way to validate a manually washed dissolution vessel, i.e., to ensure that it is significantly clean for use in the next test. The presence of any residue from a preceding test will adversely affect the results of the subsequent test. Some users wash the dissolution vessels by means of a basic rinse with clean water while others use a brush to clean the dissolution vessels. Testing facility personnel were manually cleaning dissolution vessels for many years while seeking a validated dissolution vessel cleaning method.
Beginning in about 1990, Logan Instruments Corporation of Somerset, N.J., has been producing an Automated Vessel Cleaner Model AVC-100, which is a mobile apparatus for washing dissolution vessels after use while the dissolution vessels are situated in the dissolution tester. With this apparatus, the user is able to wheel the apparatus to the dissolution tester, grasp an actuator having a washing head attached thereto and insert the washing head into the dissolution vessels one at a time. The washing head includes a vacuum tube coupled to a vacuum source, via the actuator, which is effective to remove the fluid in the dissolution vessel while water is pumped through nozzles to spray around the sides of the dissolution vessel to clean it. Water, or another cleaning fluid, is provided to the nozzles through tubes leading from a water source via the actuator. A later modification of this apparatus includes an optional heater to heat the water being sprayed around the sides of the dissolution vessel, as well as a timer to time the washing of each dissolution vessel to enable the establishment of validation protocols. The apparatus also includes a waste tank in which water removed from the dissolution vessels is stored.
One minor drawback of this apparatus is that it was found that the force of the water spray was not strong enough to ensure the dissolution vessels are thoroughly cleaned after all drug tests. Rather, in certain instances, some drug residue was found to adhere to walls of dissolution vessels such that even when using the AVC-100 apparatus, it was still necessary to apply a brush to remove residue remaining on the vessel walls after the washing head was removed from the dissolution vessel.
It would therefore be desirable to provide a head for the apparatus which almost certainly ensures that there is no drug residue remaining on the vessel walls after the washing cycle.